Combined starter and generator drive



June 1946. H. w. GILFILLAN 2,

COMBINED STARTER AND GENERATOR DRIVE Filed May 8, 1942 I 2 Sheets-Sheet 1 INVENTOR HENRY W. GILFILLAN ATTORNEYS June 25, 1946. H. w. GILFILLA N cousmzn smz'rna AND GENERATOR DRIVE v Filqd May 8, 1942 2 Sheets-Sheet 2 ATI'ORNEYS Patented June 25, 1946 COMBINED STARS.

RIVE

Henry W. Gilfillan, Detroit, Mich, assignor to Chrysler Corporation, Highland Park, Mich., a

corporation of Delaware Application May 8, 1942, Serial No. 442,157

17 Claims. 1

This invention pertains to generator drives, particularly drives for A. C. generators where constant frequency output is desired and where variable speed prime movers are employed.

More specifically, the invention relates to a drive for generators used on aircraft.

The power requirements for engine starting and for operation of auxiliaries on aircraft have steadily increased since the beginning of large scale flying activity. In military aircraft the problem of providing an adequte supply of electrical power for use on the ground and in the air has become acute because, in addition to the usual electrically operated devices commonly found on modern transport planes such as: engine synchronizers, lights, radio, propeller pitch controls, tachometers, de-icers, fuel pumps, flap controls, landing gear controls, automatic pilot, compass, brakes, etc; military craft must also include such items as: cameras, bomb releases, machine guns, cannon, etc., which are electrically operated or controlled,

The size and weight of batteries necessary for maintaining an adequate supply of ground power for engine starting and other purposes has become excessive. The use of A. C. power has obvious advantages. Alternating current power supply, however, has not been generally adopted mainly because of two objections: the speed and thus the output frequency of the A. 0. machine necessarily must vary in accordance with en ne speed, and the extraweight of the A. C. unit, which is in addition to the D. C. operated starter mechanism.

It is, therefore, the principal object of the present invention to provide an improved A. C. power supply for aircraft.

Another object is to provide a generator drive for aircraft which causes the generator to be driven at substantially constant speed regardless of variations in engine speed.

A further object is to combine the generator drive with the starter gear train thus avoiding duplication of parts and weight.

Additional objects and advantages will become apparent from the following description which describes several embodiments of the invention.

In the drawings which illustrate the principles of the invention in somewhat diagrammatic form:

Fig. 1 is a schematic view of a combined engine starter and generator drive.

Fig. lAis a section along line |A-|A of Fig. 1.

Fig. 2 is a modification of the arrangement shown m Fig.

2 Figs. 2A, 2B and 2C are sections along the corresponding section lines on Fig. 2.

Fig. 3 is a view of a further modification wherein an auxiliary internal combustion engine is used for generator speed control.

Fig. 3A is a section along line 3A-3A of Fig. 3.

Fig. 4 is a modified form of the Fig. Sarrangemerit, and

Fig. 4A is a section along line 4A4A of Fig. 4. 7 Referring now to Fig. 1, l indicates the crankshaft of the aircraft engine. The crankshaft is provided with jaws H which are adapted to be engaged by the jaws |2 of a slidable member l3. The latter is splined on a shaft I which is drivingly connected with a carrier It by means of an overload clutch I.

The carrier l3 carries a plurality of planet gears ll which mesh with the teeth ll of an annulus gear I! and the teeth Ofa sun gear 20. The sun gear is carried by a shaft 2| which is the drive shaft of an alternating current generator 22. The latter is preferably of the three phase type and has output feeders 23 which may be connected to the A. C. load. A rectifier, diagrammatically indicated at 24, is provided for converting a portion of the generator output to direct current for charging a battery 25 and supplying other D. C. operated units.

The engine starting motor 28 is D. C. operated and is connected to the output line 21 of the rectifier 21 to which the battery 25 is also connected) through a switch 28 controlled by a governor 30, and a pair of switches 29, 29 which are connected in parallel with each other and in series with switch 28 and adapted for manual operation.

The governor 30 may be of any suitable type and is driven at the speed of the generator 22.

The starting motor 26 forms part of an inertia starting system and the shaft thereof carries a flywheel 3| and pinions 32 and 33. The pinion 32 meshes with a gear 34 carried by the shaft 2| and connected thereto by means of a one-way overrunning clutch generally designated by the numeral 35. This clutch may be of any desired construction, the one illustrated (see Fig. 1A) having rollers 35 which cooperate with cam surfaces 31 formed on shaft 2| to establish a driving connection between gear 34 and shaft 2| when said gear tends to be rotated at a speed faster than the speed of the shaft. When the shaft 2| tends to rotate faster than gear 34, the rollers 38 release and permit the shaft to overrun the gear.

Pinion 33 meshes with a set of teeth 38 formed on the annulus gear I9, these teeth may be of 3 the same pitch diameter as the teeth [8 (as illustrated) or some other pitch diameter may be chosen.

The operation of the combined engine starting and generating system is as follows: let it be assumed that the main engine is dead and it is desired to start the same. Starter jaws Ii, l2 are disengaged and starting motor 26 is energized from the battery 25 by closing switches 29-29 (the switch 28 being closed when the generator is stationary).

Flywheel II is rotated in counterclockwise direction by the motor and the drive divides in two directions. Pinion 32 rotates gear 34 clockwise causing engagement of clutch 85 thereby rotating generator shaft 2i and sun gear 20 in clockwise direction. Pinion 33 drives annulus gear I! counterclockwise and planet pinions I! are likewise given counterclockwise rotation.

The ratio of the planetary gearing is such that the tendency for pinion 32 to rotate carrier 16 forwardly (or clockwise) is greater than the tendency i'or pinion 33 to rotate carrier i8 backward (or counterclockwise). The net result then is that the shaft I4 is rotated forwardly. I

When the flywheel 3i has attained the desired speed the member I3 is shifted to engage the jaws ll-i2 for starting the main engine, the inertia torque of the flywheel then being applied to the crankshaft l through the reduction gearing.

Direct cranking of the main engine may of course, be accomplished by engaging the jaws "-42 prior to energizing the motor 25.

The sleeve member I! remains engaged after i the engine is started and as the crankshaft it! comes up to speed (switch 29' being opened) in a forward direction, annulus I! which is being driven backwardly by the motor 26 becomes the reaction member of the planetary system whereupon the carrier I8 starts to drive forwardly. This causes the sun gear 20 to be driven forwardly at still greater speed and the shaft 2| will overrun the gear 34 as permitted by the overrunning clutch 45.

When the speed of shaft 2i reaches normal. the governor 30 will operate to open switch 28 and de-energize motor 26, the switch 29' having been opened manually when the main engine started. De-energization of motor 26 will of course cause the reaction torque to fall to zero and the generator speed will fall oil. This'in turn causes the switch 28 to close and the cycle is repeated. If the main engine speed falls off, governor 30 will close switch 28 and start motor 24 to drive annulus i! in backward direction thus increasing the speed of sun gear 20 and compensating for the decrease in speed of the carrier Hi. When the generator comes up to normal speed, the switch 28 will open and if the main engine is still running at subnormal speed, the cycle will repeat. The switch 28 will thus continue to "hunt'} at all times during operation of the device and the generator speed will be maintained substantially constant. A variation in generator speed (and frequency) of has been found unobjectionable.

This arrangement also makes provision for generation of ground power with the main engine dead. Under such circumstances the jaws i i -i2 are left disengaged and the generator 22 is driven by the motor 25, the power available being limited to the output of motor 26.

The table below sets forth, as an illustrative example, the gear tooth and speed relationships in a typical installation of my improved starting and generator drive:

'(Fig. 2A).

! Em No St tin Groujnd Mairtiialbo Maingrgbo ar g power aws ginea gmc at, l teeth disengaged R. P. M. R. P. M.

R. P. M. R. P. M. R. P. M. 12.1 M. as 15 -12,oo0 -11,s10 -4,s0o n 1 s2 31- -1 2,0o0 ll,6l0 -4,s0o n as 42 -4,290 -4.150 -1,714 0 1 a4 36 +1o,32o +10, 000 +4,1su n 1 1s 1o 4, 200 4,150 1, 714 n 16 20 +100 +91 +1,s00 +3.00o 1 20 so +1o,s20 +1o,o00 +1u.0o0 +104) 1 1 Pinion.

In this installation, a 12 H. P. 12,000 R. P. M. D. C. motor is employed. This gives a starting speed of 100 R. P. M. and substantially corresponds to conventional practice.

Fig. 2 illustrates a modification of the Fig. l arrangement.

In Fig. 2, the D. C. motor 40 drives a flywheel 4i and a pinion 42. The latter meshes with an annulus 43 which carries an integral pinion 44 disposed in mesh with an annulus 45. The annulus 45 is connected to the drive shaft 46 of the A. C. generator 48 by a one-way roller clutch 41 The latter operates to drivingly connect the gear 45 to the shaft 46 for forward (clockwise) drive and allows the shaft to overrun the gear in forward direction.

The shaft 4| of flywheei 4i is also adapted to drive a pinion 49 through a one-way overrunning clutch 50 which is arranged such that the shaft 4| may overrun the pinion 49 forwardly, but

- when the direction of rotation of the motor 40 is reversed, a drive is established.

The pinion 49 meshes with teeth 52 carried by an annulus 5|. The latter also carries a set of teeth 53 which mesh with planet pinions 54 carried by a carrier 55. These pinions also mesh with a sun gear 56 formed on the generator drive shaft 46. The carrier 55 is connected directly to the engine crankshaft 58 by an overload friction clutch 51.

An overrunning brake device 59 (Fig. 2C) is operatively associated with the annulus 5i and with a stationary part of the structure indicated at B0. The annulus has a reduced portion 6! which is provided with cams 62 for cooperating with rollers 83. The arrangement is such that the annulus 5| may rotate backwardly (counterclockwise), but is prevented from forward (clockwise) rotation by engagement of the rollers 83 which lock the reduced portion GI to the part 60 in a manner well known in the art.

The portion 6| also carries a shiftable sleeve 64 which has ja'ws 65 adapted to engage the jaws 65 carried by the stationary structure.

The generator 48 drives a speed-responsivc governor 51 for operating a switch 68 and the three phase output thereof is fed to the load through wires 69. A rectifier 10 supplies D. C. to the motor 40 and a battery H and the motor is connected to the D, C. source through a reversing switch 12.

The operation of the Fig. 2 device is as follows:

Starting: Switch 12 is closed, connecting terminal '14 thereof to the battery. This causes motor 40 to rotate flywheel 4| forwardly, thereby causing forward rotation of gears 42, 43, 44, 45. engagement of clutch 41, forward rotation of shaft 46 and sun gear 56 and slow backward rotation of annulus 5|, the carrier 55 taking the planetary reaction torque. When the sleeve 64 has been accelerated to desired speed, the laws 88-88 are engaged. This action stops rotation of the annulus 8| and causes carrier 88 to be r0- tated forwardly. The inertia torque of the flywheel is thus applied to the crankshaft 88 through the planetary gears and the torque limiting clutch 81. I

As the main engine comes up to speed, the carrier 88 becomes, the driving element and the switch 12 is thrown to reverse position. The latter action causes the motor 88 to reverse its rotation, switch 88 being closed until the generator comes up to speed, and overrunning clutch 88 engages thereby rotating annulus 8| backwardly. This disengages starter jaws 88-88 which are of the ramped type and the annulus 8| becomes the reaction member. The sun gear 88 then is accelerated and the generator 88 tends to come up to a rated speed. The overrunning clutch 81 disengages to permit shaft 88 to overrun annulus 88 and gears 88 88 and 88 run idly.

When the crankshaft 88 reaches running speed the governor 81 will open switch 88 and deenergize motor 88, the gear ratios being such that the generator speed will be normal at zero speed of the flywheel 8| under these conditions. If the crankshaft speed falls off, the switch 88 will close and the motor 88 will immediately start to drive the annulus 8! through the overrunning clutch 88 thereby to compensate for the decrease in speed of the generator drive.

The Fig. 2 arrangement also makes provision for ground power with the main engine dead as can be understood from the following table which illustrates the ratios and speeds of a typical installation:

Em N0 St tin Groujnd gain; c5160 11:14am en- 7 a! g power aws g ea 1 g eat3000 mam teeth disengaged P. P.

R.P.M R.P.M. R.P.M R.P. M. 42 12 +23,000 l2,000 4,800 0 43 100 +2, 760 l, 440 576 0 44 13 +2, 760 l, 440 576 0 45 100 +358 -l88 75 0 58 30 +359 +10, 000 +10, 000 +10, 080 85 +108 0 +1, 800 000 53 70 4, 290 l, 715 0 52 84 0 4, 290 1, 718 0 48 0 12, 000 4, 800 0 With this arrangement, the speed of the annulus 8| at the instant of engagement of the sleeve 88 is 154 R. P. M. backwardly which gives a starting speed to crankshaft 88 of 108 R. P. M. forwardly.

Fig. 3 illustrates a combined starting and generator drive system with speed compensation wherein an internal combustion engine i substituted for the electric motor. This scheme contemplates the use of a relatively high speed internal combustion engine, but as the speed practically obtainable with such an engine is lower than with an electric motor, the gearing is necessarily more bulky and for this reason bevel gearing is used for compactness.

In Fig. 3, the engine 88, which is preferably a gasolinevengine drives a shaft 8| which carries a pair of bevel gears 8288. The gear 82 meshes with teeth 88 of an annulus gear 88 and the gear 83 meshes with a gear 88. The latter is adapted to be connected with the shaft 81 of an A. C. generator 88 through a one-way overrunning clutch 88 (see Fig. 3A) v A shaft 88, connected to the generator shaft 81 by means of gears 8|--82, is adapted to be p 88 through the overload clutch 81.

.sleeve 88 carries laws I88 which are adapted to 'rotatably mounted on the carrier 88. The pinions 88 also mesh with teeth 88 on annulus 88. The carrier 88 drives, or is driven by, the stub shaft A shiftable engage the jaws I8| on crankshaft I82.

' In the Fig. 3 arrangement, the auxiliary engine 88 is started by cranking the shaft 88, the jaws I88--I8I being disengaged. The shaft 81 is thus rotated forwardly, the clutch 89 overrunning. The generator rotor acts as a flywheel in this instance and when the rotor has been accelerated to desired speed, the sleeve 88 (which is rotating forwardly) is engaged. This stops the planet carrier, the crankshaft I82 being resistant to rotation, and the inertia torque of the generator rotor is applied to the shaft 8| by way of the annulus 88. When the auxiliary engine 88 fires. the sleeve 88 is released as is permitted by the momentary reversal of driving torque.

The engine 88 will then drive the generator 88 through clutch 88 and furnish ground power. This arrangement permits the elimination of the battery if desired. The shaft 88 is preferably provided with a disengageable and removable crank.

When it is desired to start the main engine, the sleeve 98 is engaged whereupon the inertia torque of the generator is applied to the crankshaft M2, the reverse rotation of the engine 88 furnishing reaction torque. After the main engine starts, the engine 88 functions to regulate the speed of the generator 88 in the same manner as previously described for Fig. 1 except that the engine 88 runs continuously. The following table gives the speed relationships in a typical installation:

Main Main 1816- No. g g engine engine ment teeth ma power a a. 500 at 3000 engine) disengaged R. 1. M. a. P. M.

R.P.M.' R. P. M. R. P. M. R. P. M. 82 30 EJXX) 4, B50 2, 750 500 83 33 8.000 4,850 2,750 500 84 30 6,000 4,850 2, 750 500 86 16 +10, 320 +10, (170 +5, 670 +1, 031 96 50 5,000 4,850 2,750 as 1 13 +1 91 +1, 500 +3.00o 93 25 +10, 320 +10, 000 +10, 000 +10, (XX) 1 Pinion.

Fig. 4 illustrates a modification of Fig. 3 wherein provision is made for a two speed drive between the engine 88 and the annulus 85. The mechanism is otherwise identical with Fig. 3 and operates in a similar manner. The gear 82' is driven by the shaft 8| through an overrunning clutch I83 (Fig. 4A), the arrangement being such that the gear can overrun the shaft. A second drive gear I88 is provided which is adapted to be connected to the shaft 8| by a clutch, preferably a magnetic clutch as indicated at I88. The gear I88 meshes with a set of teeth I88 formed on annulus 88.

At low main engine speeds the clutch I88 is energized and the engine 88 exerts its torque through gear I88, while'athigh main engine speeds, the clutch I is deenergized and the clutch I83 engages to provide reaction torque through gear 82.

This arrangement is somewhat more flexible than that of Fig. 3 and the higher ratio eliminates the need for supercharging'the auxiliary engine at high altitudes. The following table gives typical operating data:

No s 'i s is. use.

' tarting power aws g e at ginc a disengaged P. a. P. M.

R. P. M. 12.1 .11. R. P. M. R. P.1il. 104 30 -5,000 -4, 850 -2, 750 -zo as as -a 000 -4, 850 --2, 750 -4:15 82' 21 14, 100 -13, 700 -7, 7m 435 106 30 5. 000 -4, 850 --2, 750 -2oo B4 50 --5, 000 -4, 850 -2, 750 200 3a 16 +10, 320 +10, 000 +5, 510 +896 85 15 -5, -4, 350 --2, 750 200 95 I 13 +100 +97 +1.50!) .2 9:; 25 +10,s2n +10.0o0 +10,o00 +10.oo0

Pinion.

The arrangements of Figs. 1 and 2 may be modified to provide for a substantial supply of D. C. during flight without the use oi a rectifier by suitably adjusting the ratio of the gearing.

For example the following table sets forth the ratios and speeds in a combined starting and generator control system such as that illustrated in Fig. 1 wherein the motor 26 will operate as a generator at high engine speeds.

F16 N0 Ground Main on Main onh Starting power jawsgine at 1800 gine at 11000 disengaged R. l. M. R. P. M.

R. P. AI. R. P. ill. R. F. AI. R. .P. it! 33 16 -10, 000 -l!), 000 +2, 140 +10, 700 32 40 -10, 000 -10, 000 +2 140 +10, 700 38 J7 l, 650 -l, 650 +353 +3, 755 34 40 +10, 000 +10, 000 2 140 l\'), 700 18 8:5 -l, 65) i,65() r3512 +1, 7B5 16 35 +100 +100 ,800 +3,000 20 J +10,U00 +10, (100 000 +10, 000

1 Ilnion.

Similarly, the arrangement of Fit. 2 may be adapted to provide a source oi ti. from the motor In as follows:

Eb ND q Groriind Mair: engian c 350 tarting power aws ginc n 1800 g e a 1 mm disengaged P. M. R. P. M.

R. P. 1U. R. P. .M'. R. P. ltl. R. P. ll" 42 13 +23,000 -l?,000 l-2,4OG +12, 000 43 39 +7, 667 4, 001') 500 +4, 000 44 14 +7, 667 4, 000 -+-8(l0 +4, 00M 45 161 +667 348 +70 +348 56 +667 +10, 000 +10, 000 +10, 000 54 +100 0 +i,80.l +1, 800 53 85 (1 +1, 765 +253 +1, 765 52 136 U -l, 765 +263 +1, 765 49 21) (l 12, 000 +2, 400 +12, 0")

Having described several ments of my invention, I wish it understood that the invention is not to be considered as limited thereby, the scope thereof being set forth in the claims appended below.

I claim:

1. In combination with an internal combustion engine having a crankshaft, engine starting apparatus including a driven sleeve adapted to be engaged with said crankshaft for starting the engine; a prime mover for driving said sleeve; reduction gearing connecting said prime mover with said sleeve; an engine auxiliary adapted to be driven by said crankshaft; means including said reduction gearing and sleeve for connecting said auxiliary to said crankshaft; and means operable by said auxiliary during operation of the. engine .tor controlling the speed of said prime mover.

2. In combination with an internal combustion power plant which includes a main engine, a

preferred embodistarting motor; gearing connecting said starting motor with said main engine; on engine auxiliary; means connecting said auxiliary with said gearing in such manner that said auxiliary may receive drive from both the main engine and the starting motor; and control means interconnecting said auxiliary and said starting motor 101' regulating the speed of the starting motor as a function of the speed of the auxiliary.

3. The combination set forth in claim 2 wherein the control means comprises a speed responsive means driven by said auxiliary.

4. The combination set forth in claim 2 wherein the auxiliary consists of a constant frequency A. 0. generator and switch means controlled by said generator as aiunction oi the speed thereof 1 or energizing said starting motor.

5. In an engine starting system, a starting sleeve adapted for engagement with the engine crankshaft; planetary reduction gearing includ-\ ing a carrier connected with said sleeve and haw ing pinions meshing with a sun gear and an an-- nulus gear respectively; a starter motor; and driving means connecting said motor withsaid annulus gear and said sun gear, comprising a shaft carried by the. sun gear, a gear carried by said shaft, a one-way clutch dispwcd between said shaft and gear, and pinion connecting said motor with the last named scar and the annulus gear, the arrangement being such that energization of said startermotor will cause both said annulus gear and said sun gear to be driven thereby.

8. In combination. with an engine havin a crankshaft, a planet gear carrier adapted for connection to said crankshaft; planet pinions carried by said carrier; annulus and sun gears respectively disposed in mesh with said piniona; a shaft carried by said sun gear; a gear on said shaft having an overrunning connection therewith; a starter motor having driving pinions disposed in mesh with said last named gear and said annulus gear whereby said crankshaft is adapted to be rotated by said starter motor for starting and said sun gear is adapted to be driven by said crankshaft under normal running of said engine.

7. The combination set forth in claim 6 where in said sun gear shaft is connected to an engine auxiliary for driving the same during operation oi the engine, and means for disconnecting the carrier from the crankshaft whereby said auxiliary may be driven by the starter motor.

8. The combination set forth in claim 6 wherein the sun gear shaft is drivingly connected to an electric generator, the ratio of the gearing being so selected that normal running speed or the engine will produce a selected normal generator speed.

9. The combination set forth in claim 6 wherein the sun gear shaft is drivingly connected to an electric generator, the ratio of the gearing being so selected that normal running speed of the tor connected with said gearing and so arranged with respect thereto that the speed thereof may be made additive or subtractive to the speed of the engine; and mean for controlling the speed engine; a speed responsive control carried by the generator, and means connecting said control with the motor such that the motor speed is controlled as a function of the generator speed.

12. In an engine starting system, a starting sleeve adapted for engagement with the engine crankshaft; planetary reduction gearing including a carrier connected with said sleeve and having pinions meshing with a sun gear and an annulus gear respectively; a starter motor; and driving means connecting said motor with said annulus gear and said sun gear, comprising a shaft carried by the sun gear, a gear carried by said shaft, a one-way clutch disposed between said Shaft and gear, and pinion means connecting said motor with the last named gear and the annulus gear,

the arrangement being such that energization of said starter motor will cause both said annulus gear and said sun gear to be driven thereby; and mean stopping rotation of the annulu gear thereby to cause the inertia torque thereof to be transmitted through said planet pinions to crankshaft.

13. In combination with an engine, a starter motor for starting said engine; an auxiliary adapted to be driven by the engine; a planetary gearset having the carrier thereof connected with the engine and the sun gear thereof connected with said auxiliary; a driving connection between said starter motor and the annulus gear of said gearset; a driving connection between said-starter motor and said sun gear, said last driving con= nection including an overrunning device permitting said sun gear to overrun said motor but preventing the motor from overrunning the sun gear.

14. The combination set forth in claim 13 wherein the driving connection between the starter motor and the annulus gear includes a pair of driven gears fixed to said annulus gear and a pair of driving gears journaled' on the shaft of said motor and means for selectively clutching said driving gears to said shaft.

15. In the combination set forth in claim 13, independently operable means for rotating the sun gear whereby said starter motor may be started.

16. In the combination set forth in claim 13 means for starting said starter motor including manually operable means for driving said sun gear. v

17. In combination, a variable speed internal combustion engine, an alternating current gen- 'erator'to be driven at a substantially constant speed drivingly connected to said engine, a motor also drivingly connected to said generator for maintaining the constant speed of the generator when the generator speed due to the drive of the engine varies, differential gearing interposed between the generator and engine and between the generator and motor to interconnect the same, the ratios of the respective input and output values of said gearing from the engine and motor to the generator being such that the algebraic sum of the speeds imparted by the engine and motor to the generator is said substantially constant speed, and motor speed control means responsive to deviations in speed of the generator from said constant speed due to deviations in the speed of the engine for impressing upon the input from the motor to the generator such speed as to return the generator speed to said substantially constant speed.

I- IENRY' w. GILFILLAN. 

